The present invention relates to the field of proximity detection devices, and more specifically to a wearable proximity detection device and a novel method of providing situational awareness and warning to the user of approaching threats from behind the user. There are currently over 500,000 correctional officers in the US with over 13,000 assaults per year. Unfortunately, there are currently no products available to help corrections officer professionals reduce their risk of being assaulted from inmates who are approaching them from behind. Besides correctional officers there are many other user groups who could benefit from a device to warn of a threat approaching from behind such as police officers, military personnel, and even civilian users such as joggers and runners for example.
There are several proximity detection devices discussed in the prior art. As a first example, U.S. Pat. Appl. Pub. No. 2015/0172545 published in June 2015 by Szabo et al entitled “Situational Awareness by Compressed Display of Panoramic Views” discloses a device that stitches video images from a camera to provide a 360 panoramic view of the surroundings to provide situational awareness. The Szabo device is a head mounted device intended for military and firefighters to wear on duty. Although the Szabo device could be used effectively for military and firefighting applications, it would be much too expensive for the average civilian to afford due to the complex array of imaging sensors and image processing hardware required.
A second example is U.S. Pat. Appl. Pub. No, 2017/0263107 published in September 2017 by Doyle et al entitled “Approaching Proximity Warning System, Apparatus and Method” discloses a wearable device that alerts the user of threats approaching from behind. The Doyle device uses short range radar to transmit and receive electromagnetic waves that bounce off of objects and processes the radar information using an algorithm to determine if there is an approaching threat from behind. The Doyle device is meant to be worn on the back of the user and will warn the user by various means such as by an audible signal or a mechanical signal such as by vibration of the device.
There are several inherent design flaws in the Doyle device that are addressed in the present invention. The first flaw inherent design flaw in the Doyle device is that it uses short range radar technology which has typically a maximum effective range of only 100 meters (328 feet). The patent pending device of Doyle and Cleghorn is disclosed on the internet by a New Mexico company known as DefendSix (www.defendsix.com). The DefendSix website product specification lists the detection range as approximately 25 meters (82 feet). With such as short detection range, there is a very high risk that the user of a DefendSix device may not have enough warning time to take evasive action if a threat such as a running person is approaching from behind. For example, based on a typical human running speed of 15 mph (22 feet per second), the Doyle device would first alert a static user when the person was 82 feet behind him. This would give the user only 3.7 seconds to take evasive action before the person contacts him if the user was standing still. Although a running user would have a few more seconds based on their speed differential, the point to be made is that the very limited range of the Doyle device leaves a very short time to take evasive action before the threat has reached the user.
The second inherent design flaw in the Doyle device is that because it uses radar it cannot discriminate a real threat from a false positive threat. For example, a bird flying towards the user will generate a warning to the user just like a person with a knife running from behind would. Although the radar would likely always warn the user once the 82 foot detection range is reached, the user over time would likely receive so many false positive warnings that he would start becoming disappointed with its effectiveness and basic lack of intelligence of the device.
Yet another inherent design flaw in the Doyle device is that its probability of detecting a target is based on a property of an object known as its radar cross section. The radar cross section of an object depends on many variables such as the object's size, surface area, shape and material. While some objects such as a large jogger running straight at a person from behind may have a large enough radar cross section for the device to warn the user, a small object such as a thrown baseball or a bicyclist might have too small of a radar cross section to reach the detection threshold depending on its distance from the radar. Because the Doyle device uses low power short range radar, the variable nature of radar cross sections will likely result in either some threats not being picked up the device or being picked up approaching too close to the user to safely take evasive action. Indeed, there is a great unfilled need to supply corrections officers, police officers, military personnel and security concerned civilians with a proximity warning device that can reliably pick up targets several hundred feet away.